Sushmita Haodijam (MBBS Student) needs a second opinion on this medical case.
Definition: Clinically respiratory failure is defined as PaO2 <60 mmHg while breathing air, or a PaCO2 >50 mmHg.
Type 1 respiratory failure - low PaO2 & low or normal PaCO2.
-Type 2 respiratory failure -low PaO2 & raised PaCO2
_TYPES OF RF:_
1. Acute hypoxia without hypercapnia - acute type 1.
2. Chronic hypoxia without hypercapnia - chronic type 1.
3. Acute hypoxia with hypercapnia - acute type 2.
4. Chronic hypoxia with hypercapnia -chronic type 2.
-Unoxygenated hemoglobin 50 mg/L
-Dyspnea: secondary to hypercapnia and hypoxemia
-Confusion, somnolence and coma
-Circulatory changes: tachycardia, hypertension, hypotension
-Polycythemia: chronic hypoxemia-erythropoietin synthesis
-Pulmonary hypertension: Cor-pulmonale or right ventricular failure.
ACUTE TYPE 1 RF:
-acute respiratory distress syndrome.
-Treat underlying condition.
-High conc of oxygen.
CHRONIC TYPE 1 FAILURE:
-diseases associated with pulmonary fibrosis.
-chronic chest wall or neuromuscular diseases.
-chronic pulmomary edema pulmonary thromboembolism.
-Treat underlying cause.
-Venesection to reduce haematocrit for polycythemic.
-Diuretics to reduce peripheral edema.
ACUTE TYPE 2 RF:
-depressant drugs like diazepam, opiates & alcohol.
-brainstem damage from stroke & trauma.
-disorders of nerves & neuromuscular transmission like GBS.
-Disorders of muscles like acute polymyositis.
-severe airflow obstruction.
-chest injuries resulting in tension pneumothorax-flial chest.
-treat underlying condition.
-oxygen therapy 24% oxygen.
-removal of secretions by coughing or emergency bronchoscopic aspirations.
CHRONIC TYPE 2 PF:
-Chestwall abnormalities like gross kyphoscoliosis.
-treat underlying cause.
-oxygen therapy carries the risk of rise in PaCO2 resulting in confusion, drowsiness.
-measure ABG levels before oxygen therapy.
-do not give more than 24% oxygen.
-give oxygen continously not intermittently at a rate of 1-2 litre/min.
-stimulant drugs advocated like doxapram hydrochloride.
-mechanical ventilation reserved for non respondant.
-supportive treat includes antibiotics, nebulisers,clearing secretions by coughing, suction.
Mechanical Ventilation (MV):
-Non invasive with a mask.
-Invasive with an endobronchial tube.
-MV can be volume or pressure cycled -For hypercapnia:
•MV increases alveolar ventilation and lowers PaCO2, corrects pH.
•Rests fatigues respiratory muscles.
•O2 therapy alone does not correct hypoxemia caused by shunt.
•Most common cause of shunt is fluid filled or collapsed alveoli (Pulmonary edema).
Positive End Expiratory Pressure:
-PEEP increases the end expiratory lung volume (FRC).
-PEEP recruits collapsed alveoli and prevents recollapse.
-FRC increases, therefore lung becomes more compliant.
-Reversal of atelectasis diminishes intrapulmonary shunt.
-Excessive PEEP has adverse effects
•decreased cardiac output
•barotrauma (pneumothorax, pneumomediastinum)
•increased physiologic dead space
•increased work of breathing